PROJECT SUMMARY/ABSTRACT Opioid Use Disorder (OUD) is a key driver of the current opioid epidemic in the United States. Nearly 80% of individuals with OUD do not receive treatment. Buprenorphine Medication Assisted Treatment (MAT) is an effective form of care for OUD. Buprenorphine ameliorates craving and withdrawal, and reduces illicit opioid use, mortality, and problems associated with drug use. However, adoption of buprenorphine in clinical practice is not yet commensurate with patient need. In addition, poor induction experiences and medication nonadherence are associated with high likelihood of treatment drop out and relapse. The perceived need for observed buprenorphine induction contributes to providers? unwillingness to prescribe buprenorphine to patients, thereby limiting patients? access to standard of care. Maximizing the efficacy and accessibility of existing pharmacotherapeutics is critical to helping individuals with OUD receive optimal and necessary care. Thus, an urgent need exists to improve medication adherence and provide strategies to alleviate potential barriers to implementation of buprenorphine in clinical practice (e.g. induction support). The premise of this proposal is to develop a state of the art, digital therapeutic that 1) effectively promotes buprenorphine adherence by providing contingency management rewards and educational content to reinforce the importance of medication in recovery and 2) effectively assists home induction with a new self-monitoring support tool designed for patients. This solution, named reSET-O+, will be integrated with Pear Therapeutics? reSET-O, an FDA market-authorized mobile application delivering validated behavioral therapy and intended for use in conjunction with buprenorphine and standard outpatient treatment for OUD. Phase I of this proposal will focus on developing and testing a functional reSET-O+ prototype to establish feasibility (e.g. acceptability) in patients with OUD. Phase II efforts will expand, refine and validate the reSET-O+ intervention. Phase IIa will use iterative patient feedback to expand the medication adherence-based contingency management system and refine buprenorphine-related content and features. A small randomized controlled trial comparing reSET-O+ to reSET-O will evaluate efficacy (e.g. induction success and medication adherence), safety, and patient engagement in Phase IIb. reSET-O+ will provide an innovative approach for OUD treatment that addresses shortcomings in the current standard of care such as buprenorphine uptake and adherence. A widely accessible digital therapeutic which effectively supports induction and adherence to buprenorphine, and is integrated within a validated behavioral therapy, is likely to promote recovery by facilitating treatment retention, relapse prevention, and better clinical outcomes. Given the number of individuals in need of MAT and the impact medication nonadherence has on patient outcomes, there is a substantial need for reSET-O+.